This invention relates generally to the control of power supplies. More particularly, this invention relates to a technique for isolating a trigger circuit of a silicon-controlled rectifier used to control a power supply.
High voltage applications of power electronic switches require that many power electronic devices be in series. Each of these devices must have a gate trigger circuit and this circuit must have voltage isolation. This voltage isolation is typically attained by using transformers with isolated windings.
It would be highly desirable to achieve voltage isolation without incurring the expense of transformers with isolated windings.
An apparatus for isolating driver circuits from silicon-controlled rectifier (SCR) circuits in a power electronics switch. Driver circuits, including an infrared emitter, are included in a driver circuit board. Switch circuits, including a SCR and an infrared detector, are included in a SCR circuit board. A plurality of electrically insulating bodies are positioned between the driver circuit board and the SCR circuit board. The electrically insulating bodies each enclose a light-pipe to optically link the infrared emitters to the infrared detectors.
The driver circuits and the switch circuits of a power electronics switch must be electrically isolated. Yet, the control signals must be sent from the driver circuits to the switch circuits. According to the present invention, electrical isolation is accomplished by the electrically insulting bodies that separate the driver circuits board and the and SCR circuit board. Signal communication between the driver circuits and the switch circuits is accomplished by the infrared emitters, the infrared detectors, and the light-pipes. The electrically insulting bodies also acts physical mounting structures for the light pipes.